Selective transmission and reception of wireless impulses



May 14, 1929. w '5 NcH 1,713,468

SELECTIVE TRANSMISSION AND RECEPTION OF WIRELESS IMPULSES Filed May 26, 1 924 Marni" 3175,3 eyed M T Prinhr Selcding Magnets INVENTOR William GHF'mcH Patented May 14, 1929.

UNITED STATES WILLIAM G. H. FINCH, 01 NEW YORK, N. Y.

SELECTIVE TRANSMISSION AND RECEPTION OI WIRELESS IIPULSH Application filed May 28,

My present invention, which is a continuation in part of an application filed by me Aug. 18, 1922, Serial No. 582,754, relates generally to apparatus employed for the transmission and reception of electrical impulses and more particularly to the transmission and reception of such impulses at radio frequencies and has special reference to the provision of radio transmitting and receiving systems for selectively sending and receiving impulses for operating devices such, for example, as recording mechanisms.

A prime desideratum of my present invention comprehends the provision of a system or apparatus operating relatively large power consuming mechanisms by remote control at radio frequencies, such mechanisms comprising, for example, vehicle control means, special recording means, printing means, such, as for illustration, typewriters. In operating this type of mechanism over long distances at radio frequencies, considerable difficulties have been experienced in translating the impulses received by existing radio receiving circuits with suflicient effect to properly influence the operating devices, heavy and sluggish in action requiring not only energy of the proper magnitude to produce the desired result but requiring also translating devices of a high degree of sensitiveness. Moreover, to obtain the maximum efliciency of operation the radio receiving system must be tuned to yield the best energy results. In operating signal recording or printing means, such as typewriters or example, I have found that existing apparatus is ineffectual for translating radio impulses into mechanism actuating impulses, such apparatus being generally too sluggish, non-sensitive and weak for the purpose intended, especially so when used with weak incoming waves transmitted from a relatively distant station. To render efi'ectual such impulse translation and to provide efficient apparatus for operating, by means of radiant energy, relatively heavy energy consuming mechanism is a principal obje'ct--of, t he invention.

The principal objects of the invention may be said to include besides the provision of apparatus of the nature referred to, the pro-' vision of such apparatus for producing selective signals and transmitting such signals for the selective operation of mechanism, such as signal printing means, the further 1924. Serial No. 715,878.

provision of a selective signalling apparatus employing a. sln le sending station and a single channel 0 communication; the further provision of such a selective signalling of constant frea radio selective system employing waves quency; the provision of system dependent upon the repetition of impulses of constant frequency and uniform duration; the rovision of a radio sending apparatus in w ich a relay controls the hi h frequency circuit; the provision of a ra io receiving apparatus employing currents of successively vision in a radio receiving apparatus of a plurality of relays of varying character of sensitiveness; the provision of a new and improved relay; the provision in a wireless receiver having multiple stages of amplification of means for varying the impedance of the external circuit of the last stage of amplification; and the provision generally of a new and improved wireless typewriter, and of a new and improved relay.

For the purpose of attaining these objects and such other objects as may appear or be pointed out hereinafter, I have illustrated an embodiment of my invention in the accompanying drawings wherein:

Figure 1 1s a diagrammatic showing of the transmitting apparatus;

Figure 2 is a similar showing of the receiving apparatus;

Figure 3 shows the tape feeding and contact making mechanism in one osition;

Figure 4 shows the tape feeding and contaccf making mechanism 1n another position; an

Figure 5 shows ceiving end.

In the embodiment illustrated in the drawings, I have shown my invention as employed for the automatic operation of printing mechanism such as a typewriter 10. (See Figure 2.) Where such mechanism is to be operated at a distance by an electric current transmitted at radio frequencies and in which a single channel of communication is employed, problems of electric transmission and reception of selection at radio frequencies and operation at audio frequencies are involved. Upon viewing Figure 1 of the drawings, it will be observed that I have here illustrated the sending apparatus generally and that the signals are transmitted at radio frequencies by means of the transmitter 16. In other words, it will be clearly understood the distributor at the reincreaslng strength; the, pro-' that I pmploy but a single sending station 11, and'I will further premise that the radio frequency, and consequently the wave length, from. the aerial 11 may be at all times maintained uniform and constant. In other words, although I employ a single station and a constant wave length, yet secure the desired selection in the manner which I will now describe.

For purposes of convenience, I Wlll from now on describe my invention as arranged to be operated at one end by a typewriter having a conventional keyboard, to operate another typewriter provided with the conventional printing mechanism. The operating typewriter (not shown) is arranged when its keys are depressed instead of printing as usual to perforate a strip or ta e such as that shown at 12 in Figure 1. E'ac operation of a typewriter key is arranged to cut one or more perforations in a row transversely of the strip and then give a feed thereto. The rows of perforations produced by the different keys willgall vary, either as to the number of perforations or as to their position, or both. For instance, in the tape illustrated, the maximum number of perforations in-a row are five. Where, therefore, a row is found which has but four perforations, it may answer to any one of five keys, depending upon which of the five possible perforations is absent therefrom. The operation of the typewriter will produce the strip or tape shown at 12 in Figure 1.

The tape 12 thus produced is then passed through the mechanism diagrammatically shown at 13, which I will term the transmitter control. This is provided with five plungers which are arranged to register with the position of the five possible perforations and as the strip 12 is fed step by step to bring each row of perforations in position above these five plungers, these plungers are reciprocated in succession from one end to the other, and where a lunger in its reciprocation finds a perforation thereabove, it is permitted to pass through, upon which it operates an electrical contact to produce an electrical impulse. Let use assume again, for purposes of illustration, that the row presented to the plungers has four perforations. There will be four successive electrical impulses produced with an interval or pause either at the beginning or at the end or in between two of the impulses. In other words, each row of" perforations will produce one or more electrical impulses, varying from all otherrows either as to the number of impulses, or as the duration or the time of the pauses therebetween.

In Figs. 3 and 4 of the drawing, I have illustrated sufficient of the tape feeding and contact making mechanism of the Kleinschmidt system to move the tape and opera tion of one of the plungers and which can be employed with m apparatus for the purposes of producing t e succession of impulses which make up the signals.

The tape that is repared by the perforator is fed throug the transmitting distributor and is stepped forward by means of the cam 145 and the pawl 146 once for every half revolution of the transmittin shaft 150 (Fig. 3) For every revolution 0% the transinittmg shaft two characters are sent over the The transmitting cam shaft 150 is motordriven through a friction clutch at any desired speed from 40 to 80 words per minute. As the shaft 150 revolves, the cam 151 moves lever 152 about a pivot 153 allowing the spring 154 to draw the pin 155 upward. If a hole in the perforated tape presents itself above the pin 155, the latter pin will pass through the tape and the contact tongue 156 will move over against its negative or marking contact as shown. If, however, the pin 155 is blocked by the tape, the contact tongue 156 will remain against its ositive or spacing contact as illustrated in i 4. Six cams 151, six levers 152, and five pins 155 are located one behind the other and operate in succession.

The contact tongue is connected directly to the local circuit 14. Positive and negative impulses are therefore sent over the line as the five pins 155 move upward, one after the other, and are blocked or are not blocked in accordance with the perforations in the tape.

At the beginning of every character one of the cams on the transmitting shaft 150 actuates a train of mechanism similar in every respect to that described above, except that no vertical pin 155 is included. At the beginning of each character the transmitting tongue moves to the right and sends out a marking impulse. This impulse is followed by the five selecting impulses and then a spacing impulse.

For every character transmitted, therefore, seven impulses are sent to the receiving station. Two are for synchronizing purposes and five are for selecting purposes. Communication is carried on at a line frequency of seven units or three and one-half cycles per character. Sixty words per minute represgnts a line frequency of 21 cycles per secon The transmitting cam shaft 150 is not stopped after each character but revolves constantly, sending out another until the sending station wishes to stop transmisison, which may be done at any time by moving a lever in the path of a stop arm attached to the transmitting cam shaft 150. When the cam shaft is stopped transmission ceases although the motor continues to drive the friction clutch through which the cam shaft is driven.

If, for any reason, it is desired to repeat a character a number of times, the button 160 (Fi 4) may be depressed so as to hold the pawl 146 out of enga ement with the ta e feed wheel ratchet. In t is way the tape Wlll remain stationary and the same character will be sent over and over again as long as the transmitting cam shaft 150 continues to re-' volve and the button is depressed.

Figure 5 illustrates the general character of the distributor at the receiving end.

The receiving distributor is entirely separate from the transmitting distributor. This necessitates two motors, but with this arrangement transmission may be carried on in T opposite directions at different speeds and accurate speed adjustments are not necessary.

The light brush arm 162 is clutch-driven at a speed slightly faster than the speed of the transmitting cam shaft at the sending end. This increased speed at the receiving station is compensated for by delaying the brush arm, after sufiiciently to keep the sending and receiving stations in step.

The brush arm 162 is rotated to selectively make contact and energize the magnets 0 erating the plungers of the printing mechanism.

Upon viewing Figure 1, it will be observed that these electrical impulses from a source such as a battery (not shown) pass over the local circuit 14 to operate a relay 15, the lVheatstone relay being found satisfactory to me.

This relay 15 in turn operates to control the transmitting circuit at radio frequencies shown generally at 16, having the aerial 11. At 17 I show the double pole, double throw switch to connect this high frequency circuit for controlling it alternately with either the relay 15 or the hand key 18.

The transmitting circuit as shown in Fig. 1 of the drawing comprises the antenna 11, inductance 90 and ground 91. A vacuum tube oscillator is shown energizing the antenna system. The oscillator comprises a set of two vacuum tubes 92 and 93 having grids 94 and 95 connected in parallel and plates 96 and 97 connected in parallel. The filaments 98 and 99 of the vacuum tubes are parallel connected and energized by battery 100. The plate circuit of the oscillators is completed through the inductance 100' and source of potential or generator 101 back to the filament side of the tubes. The grid circuit of the oscillator connects through grid leak 102 and antenna inductance 90 back to the plate connection on the oscillator. The grid circuit of the oscillator is broken by relay armature 15 and contact 104 for starting and stopping oscillations in the antenna system in accordance with the number and position of the perforations in each row on the tape 12. This relay circuit is connected to terminals DE on the transmitter.

each character is "received,

In this manner, I secure automatically the sending from a single station such as the transmitter 16, of selective signals which conslst of impulses, all of the same fr uency, the signals differing from each other y the number of repetitions of this impulse, the intervals there-between and the position of these intervals.

These impulses of radio frequency thus sent out from the aerial 11, when received by the aerial 20 (see Figure 2) are conveyed to the circuit to which the reference character '21 has been applied in Figure 2.

Referring to Fig. 2 of the drawings, the radio receiver comprises an antenna system 20, a primary receiving inductance 110, series condenser 111 and ground 112. Inductively associated with the primary winding 110 is secondary winding 113 tuned by variable condenser 114. This adjustable circuit is connected through grid leak and grid condenser 115 with thermionic vacuum tube 116 having heated filament 117, grid 118 and plate 119. The plate circuit includes coupling coil 120 inductively associated with the secondary inductance 113and including primary 121 of transformer 122 and high potential battery 123. The filament 117 is energized by battery 124. The circuit is adjustable for both heterodyne and regenerative reception. The transformer 122 has its secondary winding 125 connected to the input circuit of vacuum tube amplifier 126. The am lifier comprises vacuum tube 126 having fi ament 127, grid 128, and plate 129 and output circuit 130 and 123. The filament 127 is heated by battery 124. The winding 130 forms the primary for transformer 131', the secondary winding 131 of which is connected to the input circuit of vacuum tube am lifier 132. The vacuum tube 132 comprises t e filament 133 energized by battery 123, grid 134, and plate 135.

In the practice of my invention where I employ the Kleinschmidt apparatus as already referred to, I may use distributors at the receiving and transmitting end of the character employed in that purpose.

For the purpose of providing on the one hand a current which will be suflicient to operate the energy consuming apparatus, such as that shown in the typewriter 10, and at the same time enable this operation to be controlled accurately through the weak impulses received at the circuit 21, leading from the amplifying tube 132, I have provided a plurality of local circuits 23 and 24, the circuit 23 being controlled b the relay 25, which in turn controls the re ay 26 through the local circuit 23.

The high frequency impulses from the receiving apparatus are first conveyed to the relay 25 which is so extremely sensitive that it will be operated even on the weakest impulses to close the local circuit 23 through the energy from the battery 66 to operate the relay of a heavier type such as the Wheatstone relay 26. This Wheatstone relay in turn controls a second local circuit 24. of sufficient strength to operate the mechanism 10 as and when desired.

From the description thus far iven, it will be understood that as the tape 12 18 passed through the transmitter 13a series of groups of successive impulses are transmitted, first. over the wires 14 through the relay 15 and then by wireless from the aerial 11. These impulses are then received by the aerial and then transmitted to the sensitive relay which controls the more rugged relay 26 I which in turn controls the operating mechanism 10. The series of successlve impulses 'through local circuit 24 are then employed to operate mechanism 10 in a manner that need not be herein described.

I may employ a variable condenser to make the impedance of the external circuit equal to the impedance of the internal grid circuit.

Where, however, I; employ a multi-stage radio circuit as in Figure 2, I have found that by placing the condenser (such as a variable condenser 27) only in the last stage of amplification the desired end or result is produced. In other words, it is unnecessary to employ condensers in the intermediate stage of the circuit. The real and essential work is done in this last stage, and the utilization of the condenser only in this last stage is one of the features of the present invention.

Having thus described my invention and illustrated its use, what I claim as new and desire to secure by Letters Patent is- 1. A radio signalling apparatus comprising means including a plurality of thermionic devices for receiving impulses of uniform duration at a uniformradio frequency and a recording mechanism cont-rolledv thereby, said impulse receiving means comprising a rectifying circuit and a plurality of audio frequency amplifying circuits, said recording mechanism including a relay in the outputcircuit of the last audio frequency ampli- Eying circuit, and a condenser in the grid circuit of the tube of the last amplifying circuit to match the impedance of said relay whereby the audio amplifier is maintained in a stable condition.

2. A radio signalling apparatus comprising means including a plurality of thermionic devices for receiving impulses of uniform duration at a uniform radio frequency and a typewriting mechanism controlled thereby, said impulse receiving means comprising a rectifying circuit and a plurality of audio frequency amplifying circuits, said typewriting mechanism including a relay in the output circuit of the last audio frequency amplifying circuit, and a condenser in the grid circuit of the tube of the last amplifying circuit to match the impedance of said relay whereby the audio amplifier is maintained in a stable condition.

In testimony whereof, I have hereunto signed my name.

WILLIAM G. H. FINCH. 

